. >>> in an effort to help japan deal with its nuclearthe u.s. is the u.s. is sending in some robots. they will enter areas of that crippled nuclear plant where the radiation level is simply too high for humans. the robots will send back video, as well as radiation readings and other data. meanwhile, a new test of sea water near the plant shows radiation there is at its highest level yet. >>> the nation's highest court appears ready to block a massive sex discrimination suit against walmart. the supreme court heard arguments on the suit, brought by three of the female employees. several of the justices appeared less than convinced. here's t.j. winick. >> reporter: the plaintiffs accuse walmart of passing them over for promotions, paying them less than men. >> before i got promoted, when i was asking what i need to do, i was told to blow the cobwebs off my makeup and to doll up. >> reporter: the supreme court must decide whether thousands of female employees were discriminated against, but whether they should be allowed to bring the biggest class-action lawsu